The U.S. Navy has fielded the W76-2 low-yield nuclear submarine-launched ballistic missile (SLBM) warhead, the Under Secretary of Defense for Policy John Rood said in a statement.
The new low-yield version of the W-76 warhead is being deployed on the existing Trident II (D5) missiles onboard the Navy Ohio-class nuclear-powered ballistic missile submarines (SSBN).
According to unclassified sources, the current W76-1 warhead has an explosive yield of around 100 kilotons. The National Nuclear Security Administration (NNSA) has said the low-yield version, the W76-2, would be configured “for primary-only detonation.” This could mean a yield of less than 10 kilotons.
“This supplemental capability strengthens deterrence and provides the United States a prompt, more survivable low-yield strategic weapon; supports our commitment to extended deterrence; and demonstrates to potential adversaries that there is no advantage to limited nuclear employment because the United States can credibly and decisively respond to any threat scenario”, added the statement.
The fielding of the new warhead was initially reported by the Federation of American Scientists (FAS). According to the FAS report, the first U.S. Navy submarine to deploy with the new warhead was the USS Tennessee (SSBN-734), which departed Naval Submarine Base Kings Bay in Georgia during the final weeks of 2019 for a deterrent patrol in the Atlantic Ocean.
The W76-2 low-yield warhead was first announced in the Trump Administration’s Nuclear Posture Review (NPR) unveiled in February 2018. It cited the need for additional “tailored” and “flexible” capabilities to address the danger of “coercive nuclear use” by Russia and North Korea.
The NPR stated that this new warhead would supplement existing U.S. strategic nuclear capabilities to “enhance deterrence by denying potential adversaries any mistaken confidence that limited nuclear employment can provide a useful advantage over the United States and its allies,” and that low-yield warheads would not add to the number of deployed SLBM warheads, but would replace some “higher-yield [SLBM warheads] currently deployed.”
The U.S. Congress appropriated $65 million for work on the W76-2 warhead in FY2019 and $10 million to complete the work in FY2020. The Congress also provided the Navy with $19.6 million in the FY2020 National Defense Authorization Act (NDAA) to begin integrating the warhead into the submarine force.
The NNSA completed the first modified warhead in February 2019 and delivered the first Initial Operational Capability warheads to the Navy on September 30, 2019. NNSA has not disclosed the total number of planned W76-2 warheads, although it is expected to be a very small portion of the W76 stockpile (estimated, in unclassified sources, to be around 1,300 total warheads).